FIELD OF THE INVENTION
This invention relates to shotguns and more particularly, to a shotgun choke which may he integrally shaped in the barrel of a shotgun or threaded on the end of the shotgun barrel and is designed to facilitate reduced recoil and more uniform patterns. The shotgun choke of this invention is characterized by multiple, radially-oriented blades linearly arranged and selectively spaced to define a tapered choke bore and provided with blade edges of various shape, radial spacing and size. The blades score or etch the typically plastic wad containing the shot and constrict the shot in a random force distribution, as the wad and contained shot column pass through the choke segment of the shotgun choke. Scoring of the shot-containing wad before ejection from the shotgun barrel facilitates rapid opening of the wad panels before the ejected wad can interfere with the shot column or string as the shot string leaves the wad and moves toward the target. Ports provided in the choke body communicate with gas relief passageways defined by the blade and the wad to facilitate reduced recoil and the combination of reduced recoil and superior patterning of the shot facilitate greater accuracy in firing the shotgun.
The shotgun is an extremely popular firearm for use in both sport shooting, including trap, sport clays and skeet, as well as hunting. Most modern shotguns include a "choke" located at the end of the barrel for the purpose of constricting the shot column immediately before the shot exits the barrel. This constriction is effected to control the shot pattern size, shape and density and modern shotguns usually employ an interchangeable choke system, thus enabling the hunter or user of the firearm to change chokes according to shooting conditions and targets. Modern shotgun shells, loaded with steel or lead shot, employ a tubular wad typically manufactured from a plastic material, which packages the shot and separates the shot column or string from the shotgun barrel during acceleration of the wad and encapsulated shot through the gun barrel. The wad also provides initial support for the shot and protection for both the shot and gun barrel from undesirable contact with each other when the shotgun shell is fired.
One of the problems realized in patterning shotguns and obtaining a desirable shot pattern density, is that of matching a choke to a specific shotgun barrel to provide the desired patterning characteristics. The choke is the primary element which controls the size and density of the shot pattern and typically employs a tapered inner bore to constrict the shot column before it exits the barrel. While so constricted, the shot column and the shot-encapsulating wad produce a back pressure in the barrel, which causes a radial reaction force, stressing the choke. The reaction force of the shot column and the wad during constriction by the choke define the limits of the geometric parameters of the choke, thus limiting the density of the pattern which may be achieved with a specific choke design. Under circumstances where steel shot is used as compared to lead shot, the reaction force of steel is significantly greater than that of lead, further limiting safely achievable shot pattern densities.
When fired, all shotguns produce "recoil", which is the rearward propulsion of the gun resulting from high velocity escape of gases from the end of the shotgun barrel forwardly, after exiting of the shot column or string and the wad from the barrel. To reduce this recoil, many gun barrels and chokes are provided with porting, which includes an array of holes positioned perpendicular or at an angle with respect to the longitudinal axes of the choke or gun barrel. These ports or openings provide escape for a portion of the propelling gases behind the accelerating wad and encapsulated shot column, in a direction generally perpendicular to the direction of shot column travel, and serve to reduce recoil against the shooter's shoulder.
As the wad and shot column exit the gun barrel and the choke they gradually separate and the distance between the shot column and the wad, after wad and shot expulsion from the choke, greatly effects the shot pattern density. The greater the distance of travel of the shot wad, the greater the distortion of the shot column or string, since deviation of the wad from the plane of travel of the shot string while the trailing pellets in the shot string have not yet exited the wad, causes a change in the direction of travel of that number of shot which is still unseparated from the wad, thus resulting in fewer shot in a desired target area. Another negative effect which is apparent in conventional smooth bore shotgun barrels and barrel chokes is radial spinning of the wad and shot column, caused by unavoidable imperfection in the ammunition. This effect causes an increased radial dispersion of the shot as the shot column or string separates from the wad after exiting the gun barrel, effecting a decrease in shot pattern density.
Typical of the shot pattern control devices for shotguns is the choke device detailed in U.S. Pat. No. 2,922,242, dated Jan. 26, 1960, to F. A. Pachmayr, et al. The device includes a radially variable choke tube which is prefabricated as a unit independently of the tubular body of the device. U.S. Pat. No. 3,769,731, dated Nov. 6, 1973, also to Pachmayr, details an anti-fouling shot pattern control device. The device includes an outer apertured cage mounted by an adaptor to the gun muzzle and containing a shot-passing tube spaced from the muzzle and adaptor to provide a gas release gap. Also included is an apertured interceptor serving to prevent or minimize entry of shell wad debris into the outer cage apertures. U.S. Pat. No. 3,367,055, dated Feb. 6, 1968, to E. B. Powell, details a shotgun muzzle device including a compensator and a choke. The device includes an outer tubular cage containing a removable choke tube connected to the forward end of the cage and projecting rearwardly in alignment with the gun barrel. The choke tube includes apertures through which gases are discharged and first tapers to a reduced diameter and then has a straight cylindrical portion continuing forwardly at the reduced diameter. U.S. Pat. No. 3,496,667, dated Feb. 24, 1970, to E. D. Lowery, details a "Choked Shotgun With Rifled Barrel". The improved barrel includes a full choke at its muzzle end and rifling having a specified rate of twist. U.S. Pat. No. 3,676,947, dated Jul. 18, 1972, to Ashbrook, et al, details a "Muzzle Choke" in which the forward section or diverter is provided with multiple, internally-axially extending ridges that define a wall for guiding the projectiles into relative orientation to one another. The ridges define multiple walls to establish the pattern of projectiles on a target. U.S. Pat. No. 4,071,971, dated Feb. 7, 1978, to Tornas details a "Device For Increasing and Standardizing the Scatter of Shotguns, Particularly For Skeet Shooting". The device includes a barrel having grooves with small angles with respect to the longitudinal axis of the barrel. The groove portion of the muzzle is constricted to provide a converging and then diverging wall portion and the roots of the groove define a cylinder having a diameter comparable to the diameter of the barrel. The width of the grooves is greater than the size of the shot and discharge of the shot through the barrel past the grooves produces a twisting movement which provides a uniform distribution of shot. U.S. Pat. No. 4,711,048, dated Dec. 8, 1987, to Ashbrook, details an "Anti-personnel Shotgun Choke". The shotgun choke is designed to deform the shot pattern and throw a wide pattern with a narrow vertical band, by maintaining a substantially constant width in the choke but narrowing the height of the interior of the choke in a parabolic fashion.
It is an object of this invention to provide a built-in or interchangeable shotgun choke which is characterized by multiple, radially-disposed and selectively spaced blades having blade edges of selected shape for scoring or etching the shot wad and facilitating rapid opening of the wad panels upon expulsion of the wad and the shot column or string from the shotgun to decrease interference of the wad with the shot string.
Another object of this invention is to provide a shotgun choke which is characterized by multiple, linearly-disposed, radially-oriented blades provided in the shotgun choke bore, which blades create a bore taper and define gas relief passageways communicating with multiple ports for reducing recoil, and blade edges of selected shape and size for engaging and linearly scoring the wad from a shotgun shell and promoting random constriction forces on the encapsulated shot and rapid opening of the wad panels upon expulsion of the wad from the shotgun choke and substantially undistorted exit of a shot pattern from the wad to the target.
Still another object of this invention is to provide a shotgun choke for removable mounting on a shotgun by means of threads, which shotgun choke includes a tapered bore segment fitted with radially-disposed, linearly-oriented, parallel blades having blade edges of selected shape and size. The blades define gas relief passageways communicating with multiple ports to vent expansion gases behind the shell wad and reduce recoil. Blade edges defined by the blades engage and linearly score or etch the wad to create longitudinal wad panel striations and facilitate rapid opening of the wad panels upon expulsion of the wad from the shotgun choke and release of the shot string, wherein the shot string is not distorted by the wad as the former travels to the target.
Still another object of this invention is to provide a new and improved shotgun choke tor integral or removable deployment on the end of a shotgun barrel, which shotgun choke is fitted with a mount segment typically having threads for engaging corresponding threads on the shotgun barrel and a tapered choke segment, the bore of which is coextensive with the bore of the mount segment. Ports may be provided in the choke segment and communicate with linear gas relief passageways defined by the shell wad and linearly-disposed, radially-oriented, parallel blades for venting expanding gases behind the wad along the blades. The blades have blade edges of selected size and shape for engaging and scoring the typically plastic wad and creating longitudinal striations in the wad panels, thus facilitating rapid opening of the wad panels upon expulsion of the wad and the shot string from the shotgun choke, to minimize contact between the shot and wad and promote undistorted exit of the shot column or string from the wad to the target with improved impact.